TABLE 1.

Current hypothesis on pathogenesis of Q fever from clinical and experimental data

Pathogenesis factor	Data in humans and experimental animals	Reference(s)
Acute Q fever (factors influencing clinical manifestations)
Host factors	Unknown
C. burnetii strain	Unknown
Route of infection	Aerosol versus intraperitoneal inoculation in BALB/c mouse and guinea pig models	183, 219
Inoculum dose	Myocarditis in guinea pigs	183
Chronic Q fever (factors influencing evolution to chronic Q fever)
Host factors
Immunosuppression	Patients with acquired immunosuppression (cancers, lymphomas, or HIV infection)	138, 286, 294, 295
	Persistent infection in athymic mice	170
	Reactivation of infection with steroids or whole-body irradiation in mice and guinea pigs	330, 331
	Endocarditis in mice receiving cyclophosphamide	17
Valvulopathy	Human endocarditis and previous valvulopathy	286, 290
	Endocarditis in guinea pigs with damaged cardiac valves	181
Pregnancy	Endocarditis in pregnant mice	351
	Chronic Q fever in pregnant mammals and women	20, 350
C. burnetii strain	Genetic heterogeneity among “acute” and “chronic” strains but lack of pathotype-specific gene in human strains	314, 348
	Experimental endocarditis with Nine Mile “acute” strain	17, 181, 239, 351